Among front forks that are interposed between a front wheel and a vehicle body of a saddle-type vehicle, there is a front fork that exerts a damping force to suppress vibrations of the vehicle body. Such a front fork includes the following: a fork main body having an annular outer tube and an annular inner tube that is inserted into the outer tube such that the inner tube can move freely in the axial direction; and a damper cartridge that is accommodated in the fork main body, and extends/contracts together with the extension/contraction of the fork main body so as to exert a damping force. The damper cartridge includes the following: a cylinder in which a fluid chamber that is filled with a working fluid is formed; an annular rod guide that is mounted on the cylinder end and closes one side of the fluid chamber; a piston rod that penetrates the rod guide and moves into/out of the cylinder; a piston that is retained by the piston rod and partitions the fluid chamber into an extension-side chamber and a contraction-side chamber; a piston passage that is formed in the piston and allows the extension-side chamber to communicate with the contraction-side chamber; and a damping valve that applies resistance to the hydraulic fluid passing through the piston passage. During extension/contraction in which the piston rod moves into/out of the cylinder, the front fork generates a damping force caused by resistance of the damping valve when hydraulic fluid of one chamber that is pressurized by the piston passes through the piston passage and moves into the other chamber (for example, refer to JP2012-167785A).
Further, JP2010-185571A discloses a fluid chamber pressurization-type front fork that includes the following: a free piston that slidingly contacts the inner peripheral surface of the cylinder and closes the side of the fluid chamber that is opposite the rod guide; and a biasing means that biases the free piston toward the fluid chamber side.